Valves are used in a wide variety of applications to generally control and/or direct the flow of fluids. In one example application, valves are used to control the flow of water through water treatment systems installed in residential and/or commercial settings. These water treatment systems include, for instance, water treatment devices such as water filters and conditioners that extract and/or replace undesirable constituents in the supplied water.
One type of water treatment device, generally referred to as a capacitive deionization device, can be used to remove electrically-charged impurities, such as ions, from a water supply. In capacitive deionization devices, a stream of water passes through one or more flow-through capacitors that include pairs of polarized electrode plates. To remove impurities from the supply water passing between the electrode plates, a voltage potential is established between the electrode plates that causes many impurities in the supply water to be attracted to and (at least temporarily) retained on one of the electrode plates, while the comparatively purified water flows from the capacitor.
The efficiency and capacity of the electrode plates are reduced during use as impurities extracted from the supply water increasingly saturate the electrode plates. To regenerate the capacity of a flow-through capacitor, the flow-through capacitor can be set to discharge the captured impurities by removing the voltage potential or by temporarily applying a voltage potential in an opposite polarity to the voltage potential established during purification. During discharge, the effluent water carrying the impurities is typically routed to a drain line.
In general, operation of most water treatment devices includes some form of a service/cleaning cycle. One or more valves can be used to adjust the water treatment device between a service state and a cleaning state. If the cycle is interrupted (e.g., a loss of line power or fluid pressure to the water treatment device), the effectiveness and efficiency of a particular cycle or of the overall device can be reduced. Sophisticated water treatment devices, such as capacitive deionization devices, are susceptible to malfunction if operated under certain conditions (e.g., without adequate fluid flow, without proper regeneration cycles, etc.). Operation of water treatment devices relies, at least in part, on adequate control of fluid to, through, and from the water treatment device, even when fault conditions are encountered.